How about 150 years? Because due to orbital decay, that is about how long it would take for everything to fall out of orbit. If there is a Kessler Syndrome, dep

How about 150 years? Because due to orbital decay, that is about how long it would take for everything to fall out of orbit. If there is a Kessler Syndrome, depending on its effect at higher orbits, it might take a few hundred more years, but definitely definitely not billions of years.